Topic: Could 3mm over-height floats have caused my extremely hard starts?

[drumstyx]

This is on a 750 K8, and the book specs 14-15mm over the body...one I measured was 17.something and the rest I didn't bother measuring to start, but set them all right around 14.2-14.5mm.

What probably happened was I rebuilt the carbs before I got the book (ordered the carb kit as soon as I knew I was getting this bike), put them away, and intended to tune them right when the book came in...I've always hate doing floats, so it's not surprising my lazy ass would have avoided that.

I'm thinking 3mm, being a rather significant amount for the K7's and K8's (earlier were specced to 25mm, so I figure wouldn't be nearly as big a deal) could this have caused my woes? It was definitely lean, and it only ran with choke, so makes sense to me!

EDIT: And to clarify, I thought it was timing, but while cranking with a timing light running, both coils are absolutely dead-on the F mark.

Second question:

Now I have my bowls off, the seal/o-rings have deformed considerably, probably due to exposure to gasoline. They seem to be attempting to revert to an O shape. Is this where you all tell me I should have used OEM o-rings, rather than the aftermarket ones that came with the kit? And speaking of, what about the brass parts? Main jets I'd think are ok, but I can definitely see the pilot screw not being quite right if it weren't exactly identical in dimensions...would I be better off going back to the old brass parts?

[BomberMann650]

Pull all the plugs and hit the start button.
If gas comes out the holes. you're flooding, and flooding leads to hydrolocking, and hydrolocking leads to the dark side.

I really need to save the infographic on clear tube testing and how to measure floats with the carbs off.

25mm is the spec from edge of the bowl to the bottom of the float.  When the carbs are tilted so the floats rest gently against the closed needle valve.  Do that CONSISTENTLY for all four carbs.  None of this "eh, close enough 4 gov't work" stuff!

Then with the bowls back on, pull the drain plugs and insert clear tubes into all four bowl drains.  Tape em up to the side of the carb bodies, hold the carbs upright and pour fuel into the main hoses. 

You should be able to watch the bowls fill on all four.  With any luck, they should stop filling about 3-4 mm below the gasket seal.

And uhhh yeah, you need better bowl gaskets.  Especially if pump gas is ruining the ones you have. 

[drumstyx]

I wouldn't say it's ruined them as in they're structurally ruined...they're still plenty pliable, not falling apart, and in-place I'm sure would have been fine. What probably happened was just that they were circular o-rings that were heated and formed, then with the heat and gasoline it started reverting.

I'd love to order new ones from Honda, but they appear to only be sold as part of a full gasket/seal set for really rather a lot of money when you're looking at 4 of them.

[drumstyx]

Also, 14-15mm is the spec for K8, according to my Clymer manual. K7 and K8 use entirely different carbs than the rest of the lineup.

As for fuel level testing, in the past I've done this by attaching a clear tube to the drain nipple, and opening up the drain -- any reason this wouldn't work instead of trying to jam a tube in the drain screw hole? Perhaps, are the earlier bowls different in that the overflow nipple doesn't double as a drain nipple?

[martin99]

Also, 14-15mm is the spec for K8, according to my Clymer manual. K7 and K8 use entirely different carbs than the rest of the lineup.

As for fuel level testing, in the past I've done this by attaching a clear tube to the drain nipple, and opening up the drain -- any reason this wouldn't work instead of trying to jam a tube in the drain screw hole? Perhaps, are the earlier bowls different in that the overflow nipple doesn't double as a drain nipple?

Correct on both counts. I think Bomber is referring to roundtops, not PDs.

Those bowl gaskets can be a pain. A little 'blob' of something like Hondabond in a few strategic places helps them to stay put while you offer the bowls up to the body.

[drumstyx]

I thought that might be the case. I'm sure these are of inferior quality to OEM (as most aftermarket parts are), but I'm OK with that for now, saving nearly $100 on seals. Worst case I get a weep and I can deal with it then. But the way these buggers are formed, I think I might just put a wee bit of hondabond or similar like you said in a couple spots.

As for hydrolocking, is that not what the overflows are for? On my Concours I have the community's carb guy putting in overflow tubes for exactly this problem, for which the Concours is known.

[BomberMann650]

My 069A's have over filled into the airbox before.  It was the strangest thing to see.  Given the airbox is on the uphill side   
Overflows are not always a guaranteed failsafe 

Obvi my limited knowledge is 550 centric.  Go with what the manual says for your bike.  But do make sure you're measuring things properly.

Consensus here on simple method of jamming a tube into the bowl drain starts with a modestly sized tube and a lighter.  Heat one end, and twist it into the bowl drain.  It will thread itself.

[drumstyx]

Turns out the gasket issue is common: http://forums.sohc4.net/index.php?topic=23190.0 which explains why the ones I took off had some sort of goop holding them in. Trouble is, now I'm almost literally watching paint dry...have to let these buggers air out before they'll go back in. All this for a float adjustment I should've done ages ago...

[drumstyx]

For posterity, the answer to my original question is a resounding yes. It started like it was nothing.

Unfortunately it then wouldn't take *any* throttle unless the choke was on, at which point it would hang on the way back down. Also it seems the level was too high (overflowing) in carb 2, so I popped em back off, adjusted all of them to 15mm, and opened the idle screws to 2 turns out from 1.5. If anything it'll be rich at idle now, which I prefer dealing with

[jonda500]

Turns out the gasket issue is common: http://forums.sohc4.net/index.php?topic=23190.0 which explains why the ones I took off had some sort of goop holding them in. Trouble is, now I'm almost literally watching paint dry...have to let these buggers air out before they'll go back in. All this for a float adjustment I should've done ages ago...

I have read that boiling them in water shrinks em back down quickly

I glue mine to the floatbowls with a little dab of superglue in each corner and any where else they want to pop out

John

[drumstyx]

Turns out the gasket issue is common: http://forums.sohc4.net/index.php?topic=23190.0 which explains why the ones I took off had some sort of goop holding them in. Trouble is, now I'm almost literally watching paint dry...have to let these buggers air out before they'll go back in. All this for a float adjustment I should've done ages ago...

I have read that boiling them in water shrinks em back down quickly

I glue mine to the floatbowls with a little dab of superglue in each corner and any where else they want to pop out

John

Hah, I was using the toaster oven!

Gosh it's a good thing I live alone.

[drumstyx]

15mm and 2 turns out seems to have done the job. Also cleaned the accelerator pump system a bit more and made sure it was working before I put the air box on. I'm assuming it's normal considering the position, but #4 accelerator pump is noticeably weaker...Makes sense considering the distance from the pump though.

Responds to throttle when warm with choke off. Smells maybe a bit rich, but I'll work that out in tuning later

[flybox1]

do you have the original (black) accel pump fuel connectors between the carbs?
these typically contain two 4mmx2mm (~7mm long) brass restrictors in each.  If omitted/lost, they can cause low fuel pressure over at #4....

[flybox1]

Also, 14-15mm is the spec for K8, according to my Clymer manual. K7 and K8 use entirely different carbs than the rest of the lineup.

As for fuel level testing, in the past I've done this by attaching a clear tube to the drain nipple, and opening up the drain -- any reason this wouldn't work instead of trying to jam a tube in the drain screw hole? Perhaps, are the earlier bowls different in that the overflow nipple doesn't double as a drain nipple?

PD float height

The drain screw controls flow OUT of the overflow tube on the bottom of the bowl. 
Attach your tube and open the screw.  Check level.  Done.

[drumstyx]

do you have the original (black) accel pump fuel connectors between the carbs?
these typically contain two 4mmx2mm (~7mm long) brass restrictors in each.  If omitted/lost, they can cause low fuel pressure over at #4....

I do, I was wondering why they felt so firm. I don't think I actually looked hard at them. It's possible the whole circuit wasn't fully primed, but obviously #2 was starting to pour all over the engine, so I called it good when I saw a little squirt at 4.

As for the fuel level -- it was a hair over the seam before on #2, which was causing it to overflow...I raised the float ~0.7mm (to 15mm). Perhaps I'm thinking about this naively, but wouldn't a 0.7mm increase in the float equal approximately 0.7mm decrease in the fuel level? If that's the case, to get it as low as that image you posted I'd have to be at 16-17mm, which does not sound right to me...

[flybox1]

You should pull the connector tubes, and spray carb cleaner into them to clear blockages.  Yes, stuff can collect in them and eventually block the accel pump squirters.

Dont get hung up on the float level # you measure.  Its irrelevant.
Its just a starting place.  Proper fuel level inside the bowl is the goal.

[martin99]

You need to check those floats very carefully. The thin plate between the two is often slightly bent in several planes, causing the paired floats to be at slightly different heights and/or not precisely parallel to each other. Sit the plate on a suitable flat surface and eyeball/measure from there. If all four are not identical to each other you may not get a uniform float level by just setting them all to 14.5mm. When I did mine by clear tube I ended up with all four as in Fly's photo, but the actual float heights when measured ranged between 14 - 16mm.